1. Field of the Invention
The present invention relates to a method for manufacturing a golf club head.
2. Description of Related Art
FIG. 7 of the drawings illustrates a conventional forging process for manufacturing a golf club head. An ingot 70 made of carbon steel or alloy steel is subjected to several forging procedures while passing through several forging molds 71a-71d. The cavities 72a-72d respectively of the forging molds 71a-71d vary in shape in sequence to thereby gradually forge the ingot 70 to a shape corresponding to the respective cavity 72a-72d, thereby forming blanks 70a-70d of a golf club head. Finally, the golf club head blank 70d is subjected to several surface finishing procedures to obtain a final product of a golf club head.
In spite of the advantages of uniform steel distribution and high strength of the golf club head made by forging, the forging molds 71a-71d are complicated in elements of a molding assembly and thus increase the cost and not suitable for mass production. Further, frequent replacement of the forging molds 71a-71d is required, as they are apt to deform under the forging pressure. Further, significant deformation of the forging molds 71a-71d occurs while forging the ingot 70 to the golf club head blank 70d during the forging process, which results in deformation of the peripheries delimiting the cavities 72a-72d. As a result, the golf club head products of a standard size could not be obtained.
FIGS. 8A through 8E illustrate another conventional process for manufacturing a golf club head by casting. A casting mold 81 having a cavity 811 is prepared, wherein the cavity 811 is configured corresponding to the specification of a predetermined golf club head. Molten wax is poured into the cavity 811 of the casting mold 81 for forming a wax mold 80 (FIG. 8A). The wax mold 80 is then removed from the cavity 811 and immersed in a solution to form a ceramic outer mold 82 (FIG. 8B). Next, the wax mold 80 is melted and flows out of the ceramic outer mold 82 (FIG. 8C). Then, molten metal liquid is filled into the ceramic outer mold 82 (FIG. 8D) to form a golf club head blank 83 (FIG. 8E). The golf club head blank 83 is then subjected to several surface finishing procedures to obtain a final product of a golf club head.
The golf club head manufactured by casting is suitable for mass production and has a low manufacturing cost. Further, the golf club head manufactured by casting has improved properties in the stretching-resistance, wear-resistance, and metal fatigue, which are almost equivalent to those of a golf club head manufactured by forging. However, undesired cinder holes 84 (or sand holes, air holes) are apt to be formed in the surface of the golf club head blank 83 during the casting process, as shown in FIG. 9. The cinder holes 84 remain in the surface of the final product of the golf club head or the dimension of the final product of the golf club head is adversely affected if the surface polishing of the golf club head blank 83 is insufficient or excessive. Further, formation of the golf club head blank 83 would not be appropriate if the ceramic outer mold 82 is not completely filled with the molten metal as a result of poor flowability of the molten metal.
Cinder holes 84 cause more serious problems to a golf club head made of a Fe—Mn—Al alloy having a high viscosity and thus having a poor casting property, resulting in disqualified products. Further, in a case that an alloy of 8620 or 4130 is used for manufacturing a golf club head, the golf club head provides a good shock-absorbing effect and a good feeling while striking the golf ball, as the alloy of 8620 or 4130 has a low hardness about HRB 80-100. However, in the above-mentioned casting process, the molten alloy could not be reliably filled in the ceramic outer mold 82 and thus fail to obtain a golf club head blank 83 with a good shape.